The Red-Headed Stranger cancelled an Aug. 18 concert at a private residence in Castle Pines Village, approximately 20 miles outside of Denver, which was slated to raise money for an animal shelter organization called Dumb Friends League.

"I was told Willie woke up and had trouble breathing, so he was taken to the hospital," Fred Bartlit, the fundraiser's organizer, told the Denver Post.

Nelson has an extensive road trip ahead of him, including more than a dozen solo gigs as well as The Railroad Revival Tour alongside Band of Horses, Jamey Johnson and John Reilly & Friends.

The legendary singer/songwriter released "Heroes" in mid-May via Legacy Records. The effort, produced by Buddy Cannon (Kenny Chesney), contains classic country songs, along with new songs written by Nelson and his son, Lukas. Guest musicians on the set include Merle Haggard, Sheryl Crow, Billy Joe Shaver, Jamey Johnson, Ray Price and Snoop Dogg, among others.

The latest release, which follows last year's "Remember Me Vol. 1," marks the first album of Nelson's new long-term deal with Sony Music, which currently owns Columbia Records, Nelson's label for 20 years of his early career.

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